Pigmented melanoma cells and cultured melanocytes express a differentiation-related glycoprotein weighing about 70-80 kilodaltons, and having an isoelectric point of about 5.2-5.6. Mattes, supra. The antigen is referred to as a pigmentation associated antigen, or "PAA." The antigen was identified previously by precipitating polyclonal antibodies from sera of a melanoma patient. The antibodies thus precipitated reacted with autologous tumor cells, pigmented melanoma cells, and with normal melanocytes. There was not reaction with non-pigmented melanomas or other types of malignant or normal cells.
Based upon the earlier work described, a murine monoclonal antibody has now been produced which is specific to pigmentation associated antigen gp70-80. The production of this monoclonal antibody, and its use to examine more extensively distribution and characteristics of pigmentation associated antigen are described.